Automatically detecting the weight of the paper used in a printer, copier or other image forming machine is desirable to help maintain good print quality. In laser printers and other electrophotographic image forming machines, the weight of the paper, as a discrete characteristic of the paper and as an indicator of paper thickness, is an important factor in determining the fusing temperature and pressure, the speed at which the paper is advanced through the printer and the transfer current needed for good print quality. Electrophotographic printers typically do not detect and automatically adjust for heavy paper--paper having a basis weight greater than about 28 pounds. Some printers allow the operator to manually select a heavy paper setting in the computer printer driver to maintain good print quality on heavy paper. Manual selection, however, is only effective if the operator is able to, and actually does, select the correct heavy paper setting. Manual selection is sometimes not practicable even for a knowledgeable and diligent operator, particularly when the printer paper is changed frequently among different weight and thickness papers and from several different input sources.